Drew Barrymore's sister Jessica found dead in her car

Drew Barrymore's sister, Jessica Barrymore, has been found dead in her car on the eve of her 48th birthday.

The half-sibling of the actress was surrounded by ''dozens of white pills" with a can of energy drink between her legs as she lay slumped behind the wheel of the vehicle, which was blocking the driveway of an apartment block in San Diego.

According to local station 10News, the body was discovered at 6am by residents who were trying to leave for work.

The Medical Examiner's Office later confirmed Jessica Barrymore's identity to the station.

Drew paid tribute to her half-sister in a statement: "Although I only met her briefly, I wish her and her loved ones as much peace as possible and I'm so incredibly sorry for their loss."

An autopsy is set to fully determine her cause of death.

Jessica's last message, posted via her Facebook account, was a post from Mystera Magazine.

It read: "Life doesn't always introduce you to the people you want to meet.

"Sometimes, life puts you in touch with the people you need to meet to Help You, to Hurt You, to Guide You, to Leave You, to Love You, and to gradually Strengthen You into the Person You Were Meant to Become.[sic]"

Jessica, the daughter of John Drew Barrymore and third wife Nina Wayne, had a history of drug and alcohol addiction and was admitted to a rehabilitation programme twice during her teens.

Her famous sister, Drew, also has a half-sister named Blyth.

Drew rose to fame at the age of six after she was cast in ET. She has publicly discussed her own battle with drink and drugs, including admitting that she took cocaine for the first time aged 12.